The kinetics of diffusion-induced grain boundary migration in this system were studied, for [100] twist boundaries, using Cu bicrystals which had been annealed at 693K for times of between 5.4 x 104 and 1.73 x 105s. The experiments were carried out on bicrystalline specimens having misorientation angles of 15, 20, 23 (S13), 25, 28 (S17), 32, 37 (S5), 40, 44 (S29) or 45º. During diffusion-induced grain-boundary migration, the boundary usually migrated somewhat unidirectionally towards one of the crystal grains, and became wavy with increasing annealing time. The migration distance at 5.4 x 104s was smaller for coincidence site lattice boundaries with a low energy than for random boundaries having a high energy. The migration rate of the moving boundary was almost constant, regardless of annealing times of between 5.4 x 104 and 1.73 x 105s. The steady-state migration rate was higher for low-energy coincidence site lattice boundaries than for high-energy random boundaries. The experimental results were analyzed quantitatively by using an energy-balance model. The effective driving force for diffusion-induced grain boundary migration was then calculated as a function of the migration rate. The calculation indicated that 75 to 93% of the chemical driving force was consumed by the volume diffusion of Zn in the untransformed Cu matrix ahead of the moving boundary. By analyzing the energy consumption, the mobility of the moving random boundary in the steady state was estimated to be 6.6 x 10-17m4/Js at 693K.

Kinetics of the Diffusion-Induced Grain-Boundary Migration of [100] Twist Boundaries in the Cu(Zn) System. Y.Yamamoto, M.Moriyama, M.Kajihara, T.Mori: Acta Materialia, 1999, 47[6], 1757-66